Electrical and Chemical Properties of the HfO2/SiO2/Si Stack: Impact of HfO2 Thickness and Thermal Budget

Abstract

In this paper, we investigate the impact of thermal budget and HfO2 thickness on the chemical and electronic properties of the HfO2/SiO2/Si stack. In the first part, we have seen that high temperature anneal at 750{degree sign}C induces both the regrowth and the reoxidation of the SiO2 interfacial layer. O1s and C1s core level shifts indicate a bias drop along the whole stack of 1.1 eV. This bias drop is ascribed both to the interfacial dipole and to fixed charges in the dielectric. In the second part, ellipsometry and ultraviolet photoelectron spectroscopy are combined to deduce the HfO2 electron affinity (1.8{plus minus}0.2 eV). This value does not change with increasing thermal budget or dielectric thickness.